Anaplastic Lymphoma Kinase (ALK) is one of the receptor tyrosine kinases belonging to the insulin receptor family (Non Patent Literature 1 and. Non Patent Literature 2). It is reported that genetic abnormalities of ALK cause production of abnormal kinases fused with other genes.
As diseases accompanied by the abnormalities of ALK, cancer and cancer metastasis (Non Patent Literature 1 and Patent Literature 1), depression, and cognitive dysfunction (Non Patent Literature 2), for example, are known, and effective therapeutic and preventive medicines these diseases are provided by providing an ALK inhibitor.
As a compound having an ALK inhibitory effect, a compound represented by formula (I) (compound name: 9-ethyl-6,6-dimethyl-8-(4-morpholin-4-yl-piperidin-1-yl)-11-oxo-6,11-dihydro-5H-benzo[b]carbazole-3-carbonitrile) and the like are known (Patent Literature 3, Patent Literature 4, and Patent Literature 5).

However, the crystal form of formula (I) has not been reported so far.